[en] It is stated that the eclipsing binary Epsilon Aur is a most peculiar binary system and it has not been explained satisfactorily. Observations of this system using the International Ultraviolet Explorer (IUE) collected at the Villafranca Satellite Tracking Station of the European Space Agency are here reported. (author)

[en] The authors summarise the results of observations of the 1967-70 activity phase in the photographic spectral range (3300-4900), and of the activity phase which started in 1977 in the spectral range 6700-3400 A and 3100-1175 A, and then compare the phenomena observed during the two outbursts. (C.F./Auth.)

[en] The spectrum of 17 Lep is dominated by numerous and strong shell lines of once-ionized metals. The shell shows a composite radial velocity structure which indicates the presence of multiple components with a velocity range between -50 and -250 km s^-1. Unlike in the visible, where these multiple components are present only during outburst, in the ultraviolet such components seem to be a permanent feature. (Auth.)

[en] Important progress has been made in the last few years in the understanding of the complex phenomena occurring in cataclysmic variables. An outstanding contribution to these advances has been provided by observations with the International Ultraviolet Explorer. The most recent results obtained in the specific cases of classical nove, old novae and recurrent novae are reviewed

[en] IUE observations at high and low resolution of Nova Aql 1918 show neither evidence of outflow nor the presence of nebular lines. This indicates that the shell ejected at the time of the outburst and surrounding the system for many years (Mustel and Boyarchuck, 1970) has by now disappeared. The high excitation spectrum presents rapid variations in the far UV and eclipse effects in the near UV that seem well correlated with the orbital phase. The observations can be interpreted in terms of phenomena occurring in or near the accretion disk surrounding the white dwarf. However, the small inclination of the orbital axis raises serious problems in trying to model the system. (Auth.)

[en] UV observations of cataclysmic and symbiotic variables with the International Ultraviolet Explorer (IUE) satellite are making fundamental contribution to our knowledge of the nature of these objects. The study of UV resonance and intercombination lines of the most abundant elements was used to diagnose the physical conditions in the disk, circumstellar region, and ejecta. Most objects display a strong UV continuum which is usually attributed to emission from the hot component and/or from the accretion disk. The exceptionally long lifetime of IUE has allowed the study of these objects during different activity phases. In the recurrent nova T Cr B, dramatic UV variations were observed during phases of optical quiescence. The UV study of the recent outbursts of the symbiotic stars AG Dra, Z And, and PU Vul, and that of CH Cyg during the activity phases associated to the formation of a jet were of particular interest. The results of multi-frequency observations (from ratio to x-rays) of some symbiotic variables, and their implications for the models are also discussed. (author). 57 refs

[en] UV spectra of the narrow emission line, X-ray emitting nucleus of the galaxy NGC 7582 obtained with the IUE instrument show a steep featureless continuum, obeying a power-law of spectral index α = 3.4 +- 0.4, close to the value of previous workers for the visible spectrum (α = 3). The visual extinction on the line-of-sight of the source of continuum was derived from the strength of the 2200 A feature, and is found to be much smaller than the one deduced previously for the emission-line region. The total energy distribution cannot be accounted for in terms of a hot star model, but is rather well represented by a power-law spectrum of spectral index α = 2.1 suffering a total absorption corresponding to Esub(B-V) = 0.45. From the presence of a jump in the continuum near 3600 A, it is estimated that hot stars must contribute approximately 30 per cent of the flux at visible wavelengths. The column density of gas in front of the source of continuum is Nsub(H) = 2.5 +- 1.7 x 10²¹ atom cm^-2, so that a low energy cut-off in the X-ray spectrum should be observed around 0.75 keV. The absence of emission lines in the UV range is consistent with the high value of the extinction for the line-emitting region found by previous workers. (author)